maven compiles all tests independetly of which tests are run

src/test/java/oving5/RPNCalcTest.java.unimplemented

@@ -0,0 +1,71 @@
+package oving5;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import java.util.function.BinaryOperator;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+public class RPNCalcTest {
+
+	private RPNCalc calc;
+
+	@BeforeEach
+	public void setUp() {
+		calc = new RPNCalc();
+	}
+
+	@Test
+	@DisplayName("Test operation without operands")
+	public void testPerformOperationWithoutOperation() {
+		assertThrows(UnsupportedOperationException.class, () -> {
+			calc.performOperation('+');
+		});
+	}
+
+	@Test
+	@DisplayName("Test execution of a simple operation")
+	public void testPerformOperation() {
+		calc.addOperator('+', (a, b) -> a * b); // Use "incorrect" definition to filter out cheating
+		calc.addOperator('l', (a, b) -> a * (a + b));
+
+		calc.push(4);
+		calc.push(3);
+		calc.performOperation('+');
+		assertEquals(12.0, calc.pop(), "The result of the calculation was incorrect");
+		assertEquals(Double.NaN, calc.pop());
+
+		calc.push(4);
+		calc.push(3);
+		calc.performOperation('l');
+		assertEquals(28.0, calc.pop(), "The result of the calculation was incorrect");
+		assertEquals(Double.NaN, calc.pop());
+	}
+
+	@Test
+	@DisplayName("Test adding operators")
+	public void testAddOperator() {
+		assertTrue(calc.addOperator('+', (a, b) -> a + b), "You should be able to add operators");
+		assertTrue(calc.addOperator('-', (a, b) -> a - b), "You should be able to add operators");
+		assertFalse(calc.addOperator('+', (a, b) -> a + b),
+				"You should not be able to add the same operator twice");
+		assertFalse(calc.addOperator('-', (a, b) -> a * b),
+				"You should not be able to add the same operator twice");
+		assertFalse(calc.addOperator('.', (BinaryOperator<Double>) null),
+				"You should not be able to add a null operator");
+	}
+
+	@Test
+	@DisplayName("Check that you can remove operators")
+	public void testRemoveOperator() {
+		calc.addOperator('+', (a, b) -> a + b);
+		calc.removeOperator('+');
+
+		assertThrows(UnsupportedOperationException.class, () -> {
+			calc.performOperation('+');
+		}, "The operator should have been removed");
+	}
+}